Current solar cell elements with a crystal silicon substrate often use an element having front electrodes made of metal on their light-receiving surface sides. The front electrodes are usually metallic electrodes called bus bars or fingers. The current solar cell elements with the crystal silicon substrate also often use back contact (BC) type solar cell elements. Both positive and negative electrodes are arranged on a non-light-receiving surface side of the BC type solar cell element without arranging the front electrodes on the light-receiving surface side. An amorphous silicon film may be arranged on the rear surface side of a silicon substrate.
For a solar cell element having a p-type substrate, it is generally preferred to locate an n/p/p+ junction between the positive and the negative electrodes. For the BC type solar cell elements, it is preferred to locate such an n/p/p+ junction between the positive and the negative electrodes arranged on the same surface side of their substrate.
The formation of the n/p/p+ junction structure is realized through two film-forming steps: a first vacuum-film-forming step, and a second vacuum-film-forming step. The first vacuum-film-forming step is a step of forming a first silicon thin layer containing an n-type silicon thin film layer. The second vacuum-film-forming step is a step of forming a second silicon thin layer containing a p-type silicon thin film layer. However, it is necessary to have at least one mask forming step, and then pattern etching in order to form each of the layers. Fewer or simpler steps would reduce costs. Therefore, there is a need for a simpler method for manufacturing a solar cell element.